Variability in the American Society of Anesthesiologists (ASA) Physical Status (PS) Classifcation Scale

The ASA PS classification is used world-wide by anesthesia providers to assess the preoperative PS of patients. This score is used in many areas of anesthesia including administrative policy-making, performance evaluations, resource allocation and reimbursement of anesthesia services. In addition, it is cited as a variable in virtually all research related to anesthesia and in many other areas of medical research as well. The purpose of this study was to assess inter-rater reliability among anesthesia providers in assigning ASA scores and discover possible sources of variability. A survey containing four general questions and 10 hypothetical case scenarios was given to 70 anesthesia providers asking them to assign ASA scores and provide rationale for their decisions. All subjects reported using the ASA PS classification routinely with nearly all finding it helpful in their practice. Unfortunately, most of the sample viewed the ASAPS as an anesthetic and surgical risk indicator. Findings demonstrate a lack of inter-rater reliability in assigning ASA PS scores with a range in eight of the scenarios of three to five and in only two of the scenarios a range of two. There were no statistical differences between CRNAs and anesthesiologists or between military and non-military providers. Several sources of variability were identified in this study smoking, pregnancy, nature of the surgery, potential difficult airway, and acute injury. This classification should not be used for administrative policy determination or for reimbursement of anesthesia services until it is revised by a multidisciplinary taskforce.